A 28-year-old woman presents with a 3-day history of bilateral conjunctival injection, watery discharge, and mild foreign body sensation. She reports that her 4-year-old son had similar symptoms 1 week ago. On examination, she has mild chemosis, follicular reaction on the tarsal conjunctiva, and preauricular lymphadenopathy. Gram stain and culture of the discharge are negative. What is the most likely diagnosis?

Explanation

## Clinical Presentation Analysis **Key Point:** The constellation of bilateral presentation, watery discharge, follicular conjunctivitis, and preauricular lymphadenopathy in the setting of contact with an infected child is pathognomonic for viral conjunctivitis. ### Distinguishing Features | Feature | Viral | Bacterial | Allergic | Chemical | |---------|-------|-----------|----------|----------| | **Onset** | Acute, often bilateral | Acute, may be unilateral | Gradual, seasonal/perennial | Immediate/acute | | **Discharge** | Watery, scanty | Purulent, copious | Ropy, thick | Watery | | **Follicles** | Tarsal conjunctiva | Absent | Giant papillae | Absent | | **Preauricular LAD** | Present (common) | Absent | Absent | Absent | | **Gram stain** | Negative | Positive (cocci/rods) | Negative | Negative | | **Contagion** | Highly contagious | Variable | Non-contagious | Non-contagious | **High-Yield:** Preauricular lymphadenopathy is a hallmark of viral conjunctivitis and is absent in bacterial, allergic, and chemical causes. ### Viral Conjunctivitis Subtypes 1. **Adenoviral (most common, 70–90% of viral cases)** - Follicular response prominent - Preauricular LAD typical - Highly contagious (hand-to-eye transmission) - Self-limited; resolves in 1–2 weeks 2. **Enteroviral (EV70, CVA24)** - Acute hemorrhagic conjunctivitis - Subconjunctival hemorrhages - Rapid onset, severe pain 3. **Herpetic** - Unilateral, vesicular lid involvement - Dendritic ulcer on cornea - Photophobia prominent **Clinical Pearl:** The negative Gram stain and culture exclude bacterial conjunctivitis. The absence of seasonal pattern, ropy discharge, and giant papillae excludes allergic conjunctivitis. The lack of chemical exposure history and immediate onset excludes chemical conjunctivitis. ### Management - Supportive care: cool compresses, artificial tears - Avoid topical antibiotics (not indicated; may delay resolution) - Strict hand hygiene and avoid eye-to-eye contact (highly contagious) - Topical antihistamines/mast cell stabilizers if itching present - Reassurance: self-limited course **Warning:** Do not prescribe prophylactic topical antibiotics in uncomplicated viral conjunctivitis — they do not prevent secondary bacterial infection and may delay viral clearance.